基于FEM-SPH耦合的TBM滚刀切削仿真与试验研究

Simulation and experimental study on cutting process of tunnel boring machine(TBM)cutters based on FEM-SPH coupled method

针对现有隧道掘进机(tunnel boring machine,TBM)滚刀切削过程有限元仿真难以复现密实核传力演化机制所致的“刀下超破、刀间欠破”问题,采用有限元方法(finite element method,FEM)和光滑粒子流体动力学(smooth particle hydrodynamics,SPH)相耦合的数值方法构建TBM双滚刀顺次回转切削的三维仿真模型,选用基于Rankine拉伸截断的摩尔-库伦(Mohr-Coulomb,M-C)弹塑性本构模型,通过模拟单轴压缩和巴西劈裂试验中试样损伤失效过程确立SPH粒子临界转化阈值,开展全尺度TBM刀盘掘进试验以验证所建仿真模型。进行多组仿真研究刀间距对切削效果、法向力、滚动力、比能的影响规律。仿真结果表明:所建仿真模型可直观复现密实核演化、侧向裂纹联通和刀间碴块飞溅等宏观物理现象;仿真与试验的滚刀平均法向力、滚动力相对误差分别为2.2%和11%,验证了仿真模型的可靠性;当刀间距在60~110 mm变化时,切削比能随刀间距增大呈先减小后增大的趋势,最优刀间距为90 mm。本研究所建仿真模型和所得研究结果可为TBM滚刀破岩研究提供新思路。

Aiming at the existing tunnel boring machine(TBM)cutter cutting process finite element simulation,it was difficult to reproduce the dense core′s force transfer and evolution mechanism,and thus the problem of"excessive breakage under the cutter and insufficient breakage between the cutters"was caused.The three-dimensional rotary cutting model including two TBM cutters was built using a coupled numerical method of the finite element method and smooth particle hydrodynamics(FEM-SPH).And the Mohr-Coulomb elastoplastic constitutive model based on Rankine tensile truncation was selected,the critical transformation threshold of FEM meshes to SPH particles was determined by simulating the uniaxial compression and the Brazilian splitting processes.The numerical model was verified by full-scale penetration tests carried out by a TBM cutterhead.Based on the numerical simulations,the influences of cutter spacing on cutting performance,normal force,rolling force,and specific energy were studied.The results showed that the macroscopic physical phenomenon of dense core evolution,side crack propagation,and chip splashing was well simulated;the errors between the numerical and experimental average normal force and rolling force were 2.2%and 11%respectively,verifying the reliability of the numerical model.The rock cutting specific energy decreased first and then increased with the increasing of the cutter spacing in between 60 and 110 mm,and the optimal cutter spacing was determined as 90 mm.The numerical model and the obtained results in this study could bring in new insights for investigating the rock cutting process of TBM cutters.